Programm external board with 1.8V using nRF52840 DK

RE: Programm external board with 1.8V using nRF52840 DK

Mechatroniker — Fri, 27 Aug 2021 10:46:36 GMT

Hello together,

I have now found a solution to program the board with 1.8V with the Development Kit.
I have used the development board from Texas Instruments TXB-EVM. There I put the CLK, the SWO and the RESET together on a level shifter and the SWDIO on a separate one to avoid interferences.
Here is the connection diagram.

Greetings and thanks for the support

RE: Programm external board with 1.8V using nRF52840 DK

Jared — Thu, 17 Jun 2021 12:26:53 GMT

Hi,

Ok, keep us updated on how it goes.

regards

Jared

RE: Programm external board with 1.8V using nRF52840 DK

Mechatroniker — Thu, 17 Jun 2021 10:43:07 GMT

Thank you for the quick feedback. I will try it with a level shifter and get back to you with a solution if necessary.

best regards

RE: Programm external board with 1.8V using nRF52840 DK

Jared — Thu, 17 Jun 2021 09:14:57 GMT

Hi,

I actually need to go back on what I said regarding programming at 1V8. The interface chip doesn't support.it after all. A level shifter might do the job but I haven't tested it myself, I think the best would be to just use an external programmer such as the SEGGER base EDU.

I'm very sorry for the confusion.

best regards

Jared

RE: Programm external board with 1.8V using nRF52840 DK

Mechatroniker — Thu, 17 Jun 2021 08:52:15 GMT

Hi Jared,

I implemented your suggestion and powered my board with an external voltage source, which I also connected to GND Detect and VTG. I now get signals on the SWDCLK and SWDIO pins when I want to transmit something in Segger Studio.

My problem is that the signals on these two pins are given out with a voltage of about 3.7V (max), but my board has only 1.8V. Can I set this directly on the J-Linker? Most J-Linkers support 1.2-5.5V, so this should be theoretically possible.
Or do I need a external level shifter?

greetings

RE: Programm external board with 1.8V using nRF52840 DK

Jared — Tue, 18 May 2021 14:14:56 GMT

Hi,

Shorting SB36 will override the reverse voltage protection and can in the worst case damage the board if you have connected more than one supply at a time. In your case specifically, since the DK will operate at a different voltage than your DUT (device under test) then I think it would be best to supply your board externally. Do not connect VDD_nRF to VCC on your board, instead connect VTG to VCC on your custom board, and the rest as you have shown in your sketch.

regards

Jared

RE: Programm external board with 1.8V using nRF52840 DK

Mechatroniker — Fri, 14 May 2021 04:22:51 GMT

Hi Jared,

[quote userid="73165" url="~/f/nordic-q-a/75040/programm-external-board-with-1-8v-using-nrf52840-dk/309518#309518"]Is there a specific reason for why you shorted SB36?[/quote]

I read this in a blog and looked it up in the SB configuration afterwards. I have pasted the excerpt from this below. I just want to make sure when I have the 5V applied to J2 via the USB and the 1.8V applied via P21, that I don't get an overvoltage at the components and they don't get damaged.

With this configuration are all PIN's operated with 1.8V or are they still coupled to the 5V?

[quote userid="73165" url="~/f/nordic-q-a/75040/programm-external-board-with-1-8v-using-nrf52840-dk/309518#309518"]DUT[/quote]

What do you mean by the DUT connection?

RE: Programm external board with 1.8V using nRF52840 DK

Jared — Wed, 12 May 2021 13:11:54 GMT

Hi,

Is there a specific reason for why you shorted SB36? It shouldn't be necessary, just make sure that you only supply one source at a time. The connection looks ok, just remember to supply the DUT externally with 1.8V.

[quote user=""]Do I have to make any settings to be able to program only with 1.8V? (Hardware or Software)
[/quote]

regards

Jared